In the light of current concern about the calorie content of foodstuffs and also about the proportion of fat and sugar therein, a number of lower calorie versions of conventional foodstuffs have been developed in which the fat content has been lowered and sugar has been replaced in whole or in part by alternative sweeteners such as the so-called "intense sweeteners": aspartame, saccharin, acesulphame K, and the like. A desirable goal is a reduction in calorie content by 25% or even more. Sugar-free foodstuffs have also been developed for diabetics and to try to reduce the occurrence of caries in teeth.
A particular problem exists, however, with milk chocolate in that legally to qualify as such it must contain at least 25% fat. (All of the percentages mentioned herein are by weight unless otherwise stated.) A typical conventional milk chocolate contains about 31% fat and has a calorie content of about 530 kcal per 100 grams. Thus a reduction to a 25% fat content, with the 6% saving being compensated for by an increase in carbohydrate content, reduces the calorie content by only about 30 kcal per 100 grams, i.e. only about a 5.7% reduction. It is clear that the sugar which forms some 45-50% of conventional milk chocolate will need to be replaced by a lower calorie ingredient in order to reach the desired 25% calorie reduction.
Sugar-free chocolate for diabetics has long been known wherein sugar is replaced by sorbitol. Unfortunately sorbitol has the same calorie content as sugar and so no energy saving ensues from its use.
However the sugar alcohols similar to sorbitol such as isomalt, lactitol, maltitol, etc. which have been recently permitted in foodstuffs have calorie contents of only about 60% that of sugar and examples of sugar-free milk chocolate compositions incorporating such alternatives are described in EP-A-0317917 and a related article by Hartmut Bollinger and Thomas Keme entitled "How to make sucrose-free chocolate" published in Zucher-und Susswaren Wirtschaft in January 1988. Although the described compositions are based on isomalt which has a low calorie content, the fat content of the described compositions is of the order of 35%, which is higher than for conventional sugar-based milk chocolate. One reason for this is that the viscosity of chocolate during its manufacture and processing increases when sugar alcohols are used in place of sugar and this is usually compensated for by the use of additional fat.
In order to reduce the calorie content of milk chocolate significantly, particularly by at least 25% so as to justify the designation "lower calorie", not only should the chocolate be essentially free from sugar, but also it should have a lower fat content than conventional sugar-based milk chocolate. Heretofore, however, it has been considered not to be possible to produce a milk chocolate not based on sugar and having a fat content of less than about 30% which is satisfactory as regards its taste, texture and mouthfeel. These physiological properties are developed chiefly during the chocolate's so-called "conching" stage in which the ingredients are subjected to an extended period of intimate grinding and mixing with access to air in order to allow undesirable aromatic components to volatilize. Although the processes that go on during conching are poorly understood, it is conventional wisdom that there should be enough fat in the composition to coat all of the other ingredients and that the conching temperature should be sufficiently high to drive off all of the undesired components in a reasonable time.
Furthermore for a milk chocolate composition not based on sugar the total amount of sugar-replacing components is generally greater than the amount of sugar used in a sugar-based milk chocolate composition, and therefore it has heretofore been assumed that the fat content of such a chocolate should similarly be high, resulting in a high calorie content thereby limiting the scope for calorie reduction.